Have students
revisit safety guidelines prior to beginning
the activity. They should consider safe use
of the space in the room and the rolling of
vehicles.

In this
activity, student groups will use a wheeled
object to study the relationship between
mass and acceleration when a constant force
is applied to the object.

Depending on
the size of the objects used, measure and
mark 1 – 5 meter distances on a flat
surface. Be sure to include the ramp in the
measurements. Using a ramp standardizes the
release method. Students place the vehicle
at the top of the ramp, line rear wheels up
with a masking tape start line and release,
without any push. Make meter sticks, meter
tapes, and rulers available for student use
during the investigation. They are expected
to measure with accuracy at all times.

The object will
be released and the time it takes to move
the distance will be recorded. Students will
need to measure the mass of their objects,
and record the time it takes to travel until
the object stops (or has negative
acceleration). Have students run several
trials before adding more mass to their
vehicles. Each addition of mass should also
be measured and recorded on a student
generated chart in their science learning
logs
(view
literacy strategy descriptions).

Students should
contemplate what problems must be considered
in this investigation. Provide access to
calculators. The experiment will be repeated
by placing additional mass in or on the
object. Try using a film canister or plastic
container half-filled or filled with sand.
Students should see that the increased mass
results in a smaller change in speed, thus a
smaller acceleration.

The teacher
should have the students identify what
changes they will see (dependent or
responding variable) and what changes they
will make (independent or manipulated
variables). The trials should be repeated to
obtain an average for each variable tested.

Students should
note variations in data collected from the
different groups, if the groups used similar
vehicles. They should discuss if the
variations fall within an acceptable range.

In addition to
the students completing a laboratory report,
summarizing activities should include a
class discussion led by teacher-guided
questioning and direct instruction as
needed, enabling students to respond either
orally or in written format to summative
questions and tasks as follows:

Make
predictions about the time it will take
the vehicle to travel the required
distance.

Use
observations and data from the activity
to give a definition of accelerated
motion.

Explain the
difference between velocity and speed
and why
velocity is expressed in both speed and
direction. Give an example of when
knowing both the speed and direction of
an object is important.

Draw and
label a diagram to represent the forces
acting on the car.

Predict how
the speed and direction will change if
the direction of the force changes.

How does a
change in the vehicle’s mass affect the
acceleration of the vehicle?

When would
students observe that with increased
mass, increased force is needed to move
the mass? (moving a refrigerator vs. a
small table, etc.)